SEATTLE — An effort is building in Congress to change U.S. marijuana laws, including moves to legalize the industrial production of hemp and establish a hefty federal pot tax.

While passage this year could be a longshot, lawmakers from both parties have been quietly working on several bills, the first of which Democratic Reps. Earl Blumenauer of Oregon and Jared Polis of Colorado plan to introduce Tuesday, Blumenauer told The Associated Press.

Polis’ measure would regulate marijuana the way the federal government handles alcohol: In states that legalize pot, growers would have to obtain a federal permit. Oversight of marijuana would be removed from the Drug Enforcement Administration and given to the newly renamed Bureau of Alcohol, Tobacco, Marijuana and Firearms, and it would remain illegal to bring marijuana from a state where it’s legal to one where it isn’t.

The bill is based on a legalization measure previously pushed by former Reps. Barney Frank of Massachusetts and Ron Paul of Texas.

Blumenauer’s bill would create a federal marijuana excise tax of 50 percent on the “first sale” of marijuana – typically, from a grower to a processor or retailer. It also would tax pot producers or importers $1,000 annually and other marijuana businesses $500.

His office said Monday it doesn’t yet have an estimate of how much the taxes might bring in. But a policy paper Blumenauer and Polis are releasing this week suggests, based on admittedly vague estimates, that a federal tax of $50 per ounce could raise $20 billion a year. They call for directing the money to law enforcement, substance abuse treatment and the national debt.

Last fall’s votes in Colorado and Washington state to legalize recreational marijuana should push Congress to end the 75-year federal pot prohibition, Blumenauer said.

Washington state officials have estimated that its legal marijuana market could bring in about half a billion dollars a year in state taxes.